Count the number of mouse clicks in one second

Question 1

I would take a look at Underscore.js's _.throttle function.

_.throttle = function(func, wait, options) {
  var context, args, result;
  var timeout = null;
  var previous = 0;
  options || (options = {});
  var later = function() {
    previous = options.leading === false ? 0 : new Date;
    timeout = null;
    result = func.apply(context, args);
  };
  return function() {
    var now = new Date;
    if (!previous && options.leading === false) previous = now;
    var remaining = wait - (now - previous);
    context = this;
    args = arguments;
    if (remaining <= 0) {
      clearTimeout(timeout);
      timeout = null;
      previous = now;
      result = func.apply(context, args);
    } else if (!timeout && options.trailing !== false) {
      timeout = setTimeout(later, remaining);
    }
    return result;
  };
};

It looks really complex, but a basic example would be:

var func = function(){alert("Only do this once every second");},
    throttled = _.throttle(func, 1000);

// Call func() three times in under a second, and
// you get 3 message boxes
func(); // alerts
func(); // alerts
func(); // alerts

// Call throttled() three times in under a second, and
// you only get a message box the first time
func(); // alerts
throttled(); // does nothing
throttled(); // does nothing

// ... wait >1 second ...
func(); // alerts
throttled(); // does nothing
throttled(); // does nothing

Question 2

example.xhtml - No frameworks, no script elements in the body and counts both left and right clicks.

Additionally you can add e.preventDefault(); at the end of the anonymous onclick event function. Keep in mind that if you're trying to protect content you will ultimately fail against anyone smart enough to realize that if it's already on their computer (memory, cache, etc) that they already have it in their possession. If you're trying to protect images you must use watermarks.

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en">
<head>
<title>Click Counter</title>

<script type="application/javascript">
//<![CDATA[
var click_left = 0;
var click_right = 0;

window.onclick = function(e)
{
 if (e.which==1) {click_left++;}
 else if (e.which==3) {click_right++;}

 alert('Left clicks: '+click_left+'\n\nRight Clicks: '+click_right);
}
//]]>
</script>
</head>

<body>

<div><p>Left or right click</p></div>

</body>
</html>

Question 3

First of all you should add check that the text edit you want to select after user clicked certain button already has focus. That will dramatically reduce loading on event queue.

Second you can implement your own button (by subclassing) and play around with options, like for example just ignore clicks which came within certain (small) interval. In case user starts spawning clicks very fast, you can also 'visualise' it on a button in certain way, showing to a user that your application had limit reactions on user input, switching it off after specified timeout.